JP5752694B2 - Microfluidic circuit - Google Patents

Description

  The present invention relates to a microfluidic circuit comprising at least one microchannel through which a first fluid that imparts at least one second fluid drop or bubble movement.

  A microfluidic circuit is disclosed in Patent Document 1 in the name of the same applicant. The microfluidic circuit is formed of a suitable material, such as PDMS (polydimethylsiloxane), typically with microchannels of about 100 μm width and about 50 μm depth. In such microchannels, very slow flows of fluids such as air, water, oil, reagents, etc. can pass.

  A laser beam whose wavelength is not absorbed by the material comprising the circuit flows or stops the flow of the first fluid in the microchannel, or crushes the first fluid into drops, or the first In order to mix one fluid with a second fluid, it is converged to an interface between the first fluid flowing in the microchannel and the second fluid present at least partially in the microchannel. By converging the laser beam on the fluid interface, a temperature gradient is generated along the interface, and fluid movement is induced by thermal capillary flow transmission.

  Similarly, as is known from US Pat. No. 6,057,049 in the name of the same applicant, this technique has been used to process drops in a microfluidic circuit having at least one microchannel through which the drops pass. The methods used are to classify drops, to form ultra-fine drops from large sized drops, or to fuse fluids contained in such drops by fusing contacted drops Including inducing a laser beam on a drop interface in the carrier fluid or on a contact drop interface to induce a reaction between.

WO2006 / 018490 WO2007 / 138178

  It is an object of the present invention to provide other methods for processing drops in a microfluidic circuit that can be used in combination with the conventional processing techniques described above.

  To this effect, the present invention relates to a microfluidic circuit comprising at least one microchannel for the flow of a first fluid carrying at least one second fluid drop or bubble, wherein the height of the microchannel is high. At least partially extending in the direction of the flow of the first fluid, and the microchannel is at least partially extending in the direction of the flow of the first fluid. And a trap region for catching drops or bubbles, wherein the trap region or the channel has at least certain drops or bubbles of the second fluid in the microchannel. The height of the microchannel is higher than the height of the microchannel so as to be guided by being pulled into a path or the trap region. Wherein the fact, to provide a microfluidic circuit.

  When drops are introduced into the fluid, the surface energy of such drops is even lower than when the outer surface is small. Thus, the minimum energy is obtained by a spherical drop and increases continuously as the drop changes from this shape. This surface energy can be calculated for a known amount of drops for any location in the microchannel. Thus, whether this drop is guided by a given flow path can be predicted by comparing it with play force.

  The crushed drop located in the microchannel has a substantial outer surface. Such drops naturally try to reduce the outer surface of the drop, and such an outer surface moves to a higher flow path when the drop reaches the branch between the microchannel and the flow path. Guide the drops into.

  Thus, the drop is pulled by the flow path and moved along the flow path by the first fluid.

  If the direction of the flow path is not parallel to the direction of flow of the first fluid (carrier fluid) in the microchannel, the first fluid causes the first fluid to drop into a direction perpendicular to the partial direction of the flow path. As long as the viscous drag force applied is weaker than the traction force required to deform the drop back to its crushed shape, the drop is positioned in the flow path.

  This phenomenon is affected by various parameters such as carrier fluid viscosity, drop fluid viscosity, drop size, carrier fluid velocity, surface tension, flow channel geometry, microchannel thickness, etc. .

  Of course, it is possible to use drops or bubbles normally without changing the operation of the present invention.

  According to a feature of the invention, the microchannel is defined by two parallel walls and the flow path is defined by a groove in at least one wall of the microchannel or the one of the microchannels. It is formed between two parallel ribs on the wall.

  At least two different types of bubbles or drops are transported by the first fluid, and the flow path is guided so that only the first type of bubbles or drops are guided into the flow path. It is advantageous to constitute a means for classification.

  As described above, in the droplet pulled by the flow path, the viscous force applied to each droplet by the first fluid is weaker than the force necessary to deform the droplet and return to the crushed shape. It is a drop.

  Conversely, a drop that flows in the direction of the carrier fluid without passing through the flow path is necessary for the viscous force applied to the drop by the first fluid to return to a crushed shape by deforming the drop. Drops stronger than force.

  As a result of this, large drops or very viscous drops are less prone to traverse the path trajectory than small drops or little viscous drops.

  According to the possibilities of the present invention, different types of bubbles or drops have different sizes or viscosities or surface tensions, which makes it possible to separate these bubbles or drops from one another. Become.

  In one embodiment, the flow path has at least two consecutive portions of different heights and / or widths, of which the larger width and / or height portions are smaller widths and / or It is arranged in front of the height portion in the direction of the first fluid flow.

  This type of flow path can easily separate two types of bubbles or drops. By way of example, strong or large bubbles will flow along only the high portion of the flow path before being discharged from the flow path by the carrier fluid, while weak or small bubbles will flow more It flows not only along the high part of the road but also along the low part.

  According to another feature of the invention, the circuit has a plurality of channels with different slopes and / or different widths with respect to the first fluid flow, so that different types of It is possible to distinguish bubbles or drops.

  The circuit has a plurality of trapping areas for catching drops or bubbles, such areas by enlarging the cross-section of a drop or foam passage in the microchannel or the flow path. Alternatively, it is effective to be formed by partially changing the surface energy of the microchannel and / or the flow path.

  The circuit may have a trap region in the microchannel even when there is no flow path. Drops or bubbles carried by the carrier fluid are trapped in the trap region located in these trajectories.

  Furthermore, such a trap area may be smaller than the size of the trapped drop or bubble.

  Such a trapping region can be adapted to a single type of foam and / or can contain only a predetermined number of bubbles, for example one or two bubbles.

  The trapping area can make single or multiple drops immovable, so that, for example, examining these drops with a microscope and / or within a certain period of time. It is possible to track the development of reactions at

  At least some of the trapping regions can be independent of each other.

  Alternatively, at least some of the trap regions are connected in series or in parallel by the microchannel or the flow path.

  The trap may be manufactured such that the presence of a drop in the trap region forces subsequent drop transport to continue and fills a trap located downstream.

  Although the captured droplet is stationary, the contents of the droplet remain in motion due to the flow of the carrier fluid. In this way, the contents of the drop can be mixed even when the drop is stationary. Such a phenomenon can play a particularly important role in the field of biological incubation or for setting up of a chemical reaction.

  Thus, it is possible to bring the drops close together or in contact with each other and fuse the drops to cause a chemical reaction, or to compare their contents.

  When trapping regions are connected in series with each other, one or more drops are trapped in the region located downstream by the cascade effect by jumping from one trapping region to the other trapping region Drop movement can occur.

  According to another feature of the invention, an obstacle is formed downstream of the trapping area so as to retain bubbles or drops drawn into the trapping area in the trapping area.

  It is advantageous that at least one flow path has means for decelerating or accelerating bubbles or drops present in the flow path. Such a means for decelerating or accelerating is a corresponding microchannel wall rail formed by deformation of the width or height of the flow path or along a predetermined area for decelerating or accelerating. Or it is formed by the rib.

  According to another feature of the invention, the circuit provides means for supplying a parallel stream of drops or bubbles of different properties into the microchannel and for introducing drops or bubbles of different properties into the microchannel. The parallel means and the introduction means are formed in the microchannel so that drops or bubbles from each of the introduction means are guided to a predetermined region of the microchannel by the introduction means. And a flow path.

  Thus, each type of drop is moved to a predetermined position in the microchannel. It is possible to place a series of drops of known nature at various levels of the microchannel.

  The present invention may be better understood by reading the following description, made by way of non-limiting example, with reference to the accompanying drawings, in which: It becomes clear.

FIG. 1 is a schematic view showing a cross section of a microchannel. FIG. 2 is a view corresponding to FIG. 1 showing another embodiment of the present invention. FIG. 3 is a view corresponding to FIG. 1 showing another embodiment of the present invention. FIG. 4 is a top view showing a microchannel provided with a flow path. FIG. 5 is a top view showing a microchannel provided with a network of flow paths. FIG. 6 is a top view of a microchannel according to an embodiment of the present invention for sorting drops of different properties. FIG. 7 is a top view of a microchannel according to an embodiment of the present invention for sorting drops of different properties. FIG. 8 is a top view of a microchannel according to an embodiment of the present invention for sorting drops of different properties. FIG. 9 is a top view of a microchannel according to an embodiment of the present invention for sorting drops of different properties. FIG. 10 is a top view of a microchannel provided with a flow path provided with means for decelerating a droplet. FIG. 11 is a top view of a microchannel provided with a flow path having means for accelerating drops. FIG. 12 is a top view of a microchannel provided with a main channel and a branched channel so as to decelerate drops in the main channel. FIG. 13 is a top view of a microchannel having no flow path and provided with a trap region for catching bubbles. FIG. 14 is a top view of a channel provided with a trap region for catching bubbles. FIG. 15 is a top view of a flow path provided with a trap region for catching bubbles. FIG. 16 is a top view of a network of flow paths having obstacles. FIG. 17 is a top view of a network of channels having a wetting region. FIG. 18 is a top view of the flow path forming the microreactor. FIG. 19 is a top view of a microchannel having a channel provided with trap regions arranged in series. FIG. 20 is a top view of a matrix arrangement of trap regions. FIG. 21 shows a microchannel with means for supplying a parallel flow of drops of different nature.

  FIG. 1 schematically shows a first embodiment of a microcircuit 1 according to the invention.

  The microcircuit 1 is applied to the plate by means of a suitable material such as PDMS (polydimethylsiloxane), for example, using conventional techniques of adaptive lithography, as known from the prior art described above. Is formed.

  One or a plurality of microchannels 2 can be formed on one side of the plate on which, for example, a glass microscope slide is bonded.

  As can be seen from FIG. 1, the microchannel 2 has a rectangular cross section, the width L of which is defined by a horizontal lateral dimension, ie in the plane of the microcircuit 1, The height h of the cross section is defined by the vertical dimension, ie in the direction perpendicular to the plane of the microcircuit 1.

  Of course, the above conditions are used only with reference to the drawings and are valid regardless of the orientation of the microcircuit.

  A groove 3 having a rectangular or square cross section is arranged on one of the two horizontal walls 4 defining the microchannel 2. According to another embodiment of the present invention, a second groove may be arranged in the opposite horizontal wall opposite said one wall 4.

  The groove 3 forms a channel having a larger cross section than the remaining part of the microchannel 2.

  A first fluid, referred to as a carrier fluid, pulls a second fluid drop 5 of a different nature from the first fluid together with the first fluid, thereby indicating in the microchannel 2 by an arrow F. Cycle in the direction that is being done.

  In the following, the second fluid may be in the form of drops or bubbles without changing the operation of the invention.

  Drops 5 that flow into a narrow region of the microchannel are crushed. When the droplet 5 reaches the flow path 3, the droplet 5 has a less crushed form, for example, a spherical shape or a substantially spherical shape, and requires a lower surface energy than the crushed form. Note that the drops may continue to be crushed while being guided by the flow path. The criterion is that the surface energy of the drops in the channel is lower than outside the channel, i.e. below the range corresponding to the lowest value of this energy.

  Then, the droplet 5 that has reached the flow path 3 circulates along the flow path 3 so as to be carried out of the flow path 3 by the carrier fluid.

  The droplets may be larger or smaller than the flow path 3.

  FIG. 2 shows another embodiment of the present invention, in which the groove defining the flow path 3 has a concave or curved shape.

  Yet another embodiment is shown in FIG. 3, in which one of the horizontal walls 4 is provided with two parallel ribs 6. The ribs 6 are spaced apart from each other and extend into the microchannel 2, and the flow path 3 is defined between the ribs 6.

  In this way, the droplets 5 crushed between the upper part of the rib 6 and the opposite wall 8 are transferred to other channels of the microchannel 2 located in the flow path 3 or on both sides of the rib 6. Led to the area. In such a region, the droplet 5 returns to a spherical shape or a substantially spherical shape, and thus the surface energy is lowered. In this way, the ribs form a barrier that allows certain drops to be separated from other drops.

  FIG. 4 shows the form of the flow path 3 in a top view. In this example, the flow path 3 has at least one portion 9 extending according to the axis A of the microchannel, ie according to the axis of the flow F of the carrier fluid, at least one extending obliquely with respect to the aforementioned axis A It has a portion 10 and / or at least one portion 11 of sinusoidal shape.

  In each of the aforementioned parts, the trajectory of the drop 5 circulating along the flow path 3 is such that the drop 5 is always pulled from upstream to downstream of the flow path 3, ie the microchannel 2, by the carrier fluid. And having components according to the direction of flow of the carrier fluid.

  In the case of the obliquely extending part 10 or the sinusoidal part 11, the movement time of the droplet 5 in the microchannel 2 is particularly longer. Thus, the contents of the drop 5 can be observed with a microscope over a long period of time without the observation region needing to be changed over a long period of time.

  FIG. 5 shows a network of channels having a central channel 12 extending in the direction of the microchannel 2. A plurality of auxiliary channels 13 extend on both sides of the central channel 12. Each of these auxiliary flow paths 13 extends from the central flow path 12 and rejoins the central flow path 12 like a branched flow path.

  In the case of FIG. 5, the droplet 5 contains water, for example, and the carrier fluid is paraffin. The width of the microchannel 2 is 3 mm, and the width of the flow paths 12 and 13 is 70 μm. The microchannel has a height of 50 μm, and the flow paths 12 and 13 have a height of 35 μm. The drops flow from left to right in the direction of arrow F.

  FIG. 6 shows the microchannel 2 in which the first fluid, which is the carrier fluid for the first and second types of drops, circulates. The first type drop 14 is larger than the second type drop 15.

  The microchannel 2 is provided with a flow path 3 extending obliquely from upstream to downstream with respect to the direction of circulation of the carrier fluid indicated by the arrow F. The height and / or width of the flow path 3 is such that the large droplet 14 is transported with the transport fluid in the direction of the arrow F, and the small drop 15 is pulled into the flow path 3 so that the flow path 3 And is adjusted so that it can be pulled from the flow path by the carrier fluid.

  The downstream end portion 16 of the flow path 3 is provided with a portion whose height or width is reduced so that the viscous force given by the carrier fluid is larger than the force necessary to crush the droplet 15. Thus, the carrier fluid pulls the drop again into the microchannel 2. The droplets 14 and 15 circulate downstream of the flow path 3 along two axes B and C that are parallel to the flow of the carrier fluid and separated from each other.

  Such microchannels make it possible to classify two types of drops having different properties.

  FIG. 7 shows a microchannel 2 that is similar to the microchannel of FIG. 6, in which the first type of drop 14 is very viscous and the second type of drop 15 is There is almost no viscosity.

  The height and / or width of the flow path 3 is such that the highly viscous drop 14 is transported with the transport fluid, and the weakly viscous drop 15 is pulled into the flow path and pulled by the transport fluid. As a result, it is adjusted so as to proceed from upstream to downstream along the flow path 3 and to exit the flow path 3 at the downstream end of the flow path 3.

  It should be noted that the stronger the drop, the stronger the force applied to the drop by the carrier fluid so that this force causes the drop to drain from the flow path.

  Such microchannels 2 can also be used to sort drops having different surface tensions.

  FIG. 8 shows the same type of microchannel as the microchannel of FIGS. In this microchannel, the flow path has regions 17, 18, 19, and 20 whose height and / or width are gradually reduced from the upstream to the downstream.

  Each region is sized so that a specific type of drop can be classified.

  In the case shown in FIG. 8, the carrier fluid pulls four types of drops of different sizes or different viscosities from the first region 17, i.e. the widest and deepest region.

  A first type of drop 21, the largest and most viscous drop, is pulled from this region 17 by the carrier fluid. The trajectory of the droplet 21 is hardly affected by the presence of the flow path 3.

  The second type droplet 22, the third type droplet 23, and the fourth type droplet 24 that are smaller than the first type droplet 21 or weak in viscosity are the first region 17 of the flow path 3. , Through this region from upstream to downstream to be transported by the transport fluid and to reach a narrower and / or lower second region 18.

  The second region 18 is sized so that the second type of drop 22 cannot pass through this region. Accordingly, such drops 22 are discharged from the flow path 3 and circulate in the microchannel 2 along an axis parallel to the flow of the carrier fluid, which is different from the axis of the initial circulation.

  In the same manner as described above, the other areas 19 and 20 of the flow path 3 are continuously passed through the first, second and third areas before the third type droplet 23 exits the flow path 3. So that the fourth type of droplet 24 circulates in the regions 17, 18, 19, and 20 of the flow path 3 before exiting from the downstream end 16 of the flow path 3. The size is set to be.

  In this way, each type of droplet 21, 22, 23, 24 circulates downstream of the flow path 3 along respective circulation axes that are parallel to each other and spaced apart from each other.

  Such microchannels thus make it possible to classify four types of drops of different nature.

  Of course, the number of different regions of the flow path can be adjusted as needed.

  In addition, as shown in FIG. 9, by arranging different flow paths 3 having different dimensions and / or inclinations in the direction of the flow F of the carrier fluid in the microchannel, various types of drops can be placed. It is possible to sort.

  In this figure, four continuous flow paths 3a, 3b, 3c, and 3d are formed in the microchannel 2, and the inclination of these flow paths with respect to the flow of the first fluid gradually decreases. . The first flow path 3a having the steepest slope separates the smallest droplet 24, the second flow path 3b separates the slightly larger drop 23, and the third flow path 3c further The large droplet 22 is separated, and the fourth flow path 3d separates the largest droplet 21.

  For example, the microchannel 2 may be provided with a flow path 3 extending along the axis of circulation of the carrier fluid, and may be provided with a portion (reduced portion) 25 having a reduced width and / or height. The reduced portion 25 may have a step, a discontinuous step, or a continuous shape as can be seen from FIG.

  In this way, the drops 5 that flow through the flow path and are transported from the flow path by the transport fluid are decelerated as they pass through the reduced portion 25.

  When the velocity of the carrier fluid is zero, the flow path geometry can be used as an engine to carry the drops. In this way, the present invention can move a drop in a two-dimensional region even when there is no flow of carrier fluid. The present invention can be used to move drops against current in relation to the flow of the carrier fluid.

  Conversely, as shown in FIG. 11, the region 26 that is gradually or stepwise expanding is accelerated so that the drops 5 circulating in the flow path 3 are accelerated as they pass through this region. It is provided on the road 3.

  The deceleration of the drop 5 can be achieved by placing a second flow path 27 on either side of the flow path 3 in which the drops are circulating (FIG. 12). The second flow path 27 has a function of partially expanding the cross section of the microchannel 2. This has the effect of partially decelerating the speed of circulation of the carrier fluid and thus the speed of circulation of the drops 5.

  Of course, the number, shape, and position of the second flow paths 27 can be changed as necessary. The important point is that the cross section of the microchannel is partially enlarged. The opposite effect can be obtained by replacing the second flow path 27 with a rib partially reducing the cross section of the microchannel 2.

  FIG. 13 shows the microchannel 2 having a trap region 28 for catching drops, formed by a pocket or cavity 29 formed in the wall of the microchannel 2. In this embodiment, when the microchannel is not provided with a flow path and the trap region is positioned on the droplet trajectory, the droplets carried by the flow F of the carrier fluid are one or more trap regions. Caught in Depending on the application, the trap region 28 may be smaller or larger than the trapped drop or bubble, depending on the nature of the drop or bubble.

  FIG. 14 shows the flow path 3 in which a trap region 28 is provided for catching a droplet formed on the wall 4 of the microchannel 2 by a pocket or cavity formed on one side of the flow path 3. .

  The pocket 29 is connected to the flow path 3 by the mouth portion 30 and can capture a predetermined number of drops. In the case of FIG. 13, this region makes it possible to accommodate only a single drop 5.

  The cross section of the mouth portion 30 can be configured depending on the application. If the mouth portion 30 has a larger cross section than the flow path 3, one or more drops 5 can be automatically pulled into the trap region 28.

  If the mouth portion 30 has a cross section smaller than that of the flow path 3 or substantially the same cross section as the flow path 3, the droplet 5 is forcibly entered into the trap region 28. May be necessary. This can be accomplished by any suitable means, particularly using the methods disclosed in US Pat. Such methods use a laser beam that is directed to the interface between the drop and the carrier fluid or between the two drops to affect the movement of the drop.

  Drops 5 can be withdrawn from the trap region 28 by increasing the flow of the carrier fluid or by discharging the drops 5 using the method described above.

  FIG. 15 shows the flow path 3 in which a plurality of trap regions 28 and 29 which are spaced apart from each other and are alternately arranged are formed on both sides. Each trap region 28, 29 captures a predetermined number of drops 5, for example one trap for trap region 28, two drops for trap region 31, and / or specific Can be sized to catch drops of the nature.

  As can be seen from FIG. 16, the microchannel 2 may be provided with a network of flow paths formed by the main flow paths 3. Drops arrive through this network, and one or more branched flow paths 31 extend from the network. The branch flow paths 31 have the drops 5 in the corresponding branch flow paths 31. An obstacle 32 is arranged that allows it to be held at least temporarily. The obstacle 32 forms a trap region. The branch channel 31 may or may not extend downstream of the obstacle 32.

  According to still another embodiment of the present invention, as can be seen from FIG. 17, the branch channel 31 may be provided with a wetting region 33. The wet area is formed by an area where the wettability of the wall 4 is changed.

  This can be accomplished, for example, by a drop of water that is stopped or slowed down in the hydrophilic region. The wettability can be changed by chemical methods, for example silanisation or plasma etching, or by introducing physical methods, for example hydrophilic rags, to fix the droplets on this (fakir effect) effect)).

  The trap region also reacts with the contents of the drop so as to form a microreactor or to detect the presence of chemical and / or biological molecules in the drop or drops. You may have elements intended to do. By way of example, a DNA sequence can be detected if a complementary sequence is partially located on the wall of the corresponding trap region.

  Several drops can be in close proximity to each other or in contact with each other, as shown in FIG. For this purpose, the microchannel has, for example, two parallel flow paths 34 and 35. Each of the flow paths 34 and 35 is for circulation of a specific type of droplets 36 and 37, and a branched flow path 31 extends from the flow paths 34 and 35. A downstream end portion 31 forms a trap region 28.

  The trap regions 28 are arranged close to or in contact with each other so that the first type of droplets 36 are close to or in contact with the second type of droplets 37.

  Thus, it is possible to fuse the two types of drops 36, 37 and to react these contents, or to compare these contents with each other.

  FIG. 19 shows a microchannel 2 having a flow path 3 provided with a plurality of continuous trap regions 28 arranged in series.

  As drops 5 are trapped in each of the trap regions 28 and further drops reach from the flow path 3, the further drops expel the drops from the upstream trap, and the ejected drops are Drops are withdrawn from a trap located directly downstream of this upstream trap. As a result, the cascade effect results in the movement of all drops 5 from one trap region 28 to the other trap region.

  The trap region 28 forms a buffer region T defined by an enlarged portion of the microchannel, in which the drop 5 causes a chemical or biological reaction, And / or is located in this region for a predetermined duration required to allow these observations.

  Further, as shown in FIG. 20, the trap region 28 includes a main flow path 3 and a plurality of branched flow paths 31 connected to a predetermined number of trap areas 28 and parallel to each other. Can have a matrix layout.

  FIG. 21 shows means 38 for supplying a parallel flow of drops 21, 22, 23, 24 of different nature, parallel means 39 for introducing drops of different nature into the microchannel 2, and means for introducing said A plurality of channels formed in the microchannel 2 so as to guide the droplets 21, 22, 23, 24 coming out of each of them to a predetermined region of the microchannel 2 by the means 39 for introducing the droplets. 3 shows a microchannel 2. Thus, a parallel flow of different drops is formed in the microchannel.

  The aforementioned microchannels for the treatment of drops in the carrier fluid may be used for the treatment of bubbles.

  The present invention in particular makes it possible to incorporate the preparation of the sample into the microfluidic chip and to give the sample to the observation point in a simple and reliable manner.

  The microfluidic circuit according to the invention can be applied in the field of biotechnology or “chimietech”, but can also be applied in the field of fluid displays and the observation of reactions in very small drops.

  Such a microfluidic circuit may have a form that has become the standard today, such as a “microarray” or biochip, such as a protein chip or a DNA chip, or a cell culture chip.

  Such biochips are composed of matrix regions whose surfaces are functionalized with biomolecules, and the size and distance between such regions is approximately the same as the size of microfluidic drops and channels. is there. The present invention relates to the use of specific drops with known inclusions to bring them to a functionalized location and to generate hybridization that allows biological measurements. Allowing contact with a surface. In this way, the present invention allows biochip technology to be combined with the effects of fluid handling in microfluidics.

  As described above, the trajectory of the drop can be actively changed by the laser to bring the drop into the trap or into a predetermined area of the microchannel.

  In the case of microchannels with multiple flow paths, such a method can be used to direct drops from one flow path to the other flow path, for example to select from various trajectories the trajectory through which the drops can pass. .

  For this reason, if the fluid has normal thermocapillary flow, the wavelength of the laser must be selected so that the wavelength is absorbed by the carrier fluid. The carrier fluid may include a colorant (eg, black ink) that absorbs the wavelength of the laser, if necessary. In this case, the droplet is guided into the channel by partially heating the carrier fluid with a laser in or near the channel. Heating can be accomplished at the interface between the drop and the carrier fluid to direct the drop into a predetermined flow path.

  If the fluid has an abnormal thermocapillary flow, the laser can be positioned to block the drop progression and divert the drop into other channels.

  Also, heating can be provided in part or in whole by an electrical heating member.

  Furthermore, if the fluid used does not absorb the laser, such absorption can be effected directly by the material making up the microchannel, or the layer or particles of the material that absorbs the laser radiation can be microchanneled or Can be accomplished by depositing in the flow path.

  Also, dielectrophoretic forces can be used to affect the trajectory of the drop or to catch the drop.

Claims (12)

In a microfluidic circuit (1) comprising at least one microchannel (2) for the flow of a first fluid carrying at least one second fluid drop or bubble (5),
The height (h) of the microchannel (2) is set to crush the drop or bubble (5) during the movement of the drop or bubble (5), and the microchannel (2 ) Has at least one flow path (3) extending at least partly in the direction of the first fluid flow (F) or a trapping area (28) for catching drops or bubbles. In the trap region (28) or the flow channel (3), at least a predetermined droplet or bubble of the second fluid in the microchannel (2) is transferred to the flow channel (3) or the trap region (28). ) as guided pulled and in the and in that has a height of a microchannel (2) (h) higher than the height (hc), microfluidic.   The microchannel (2) is defined by two parallel walls (4, 8), and the flow path is a flow path (3) of at least one of the walls (4) of the microchannel (2). 2. The circuit according to claim 1, characterized in that it is formed by or between two parallel ribs (6) of the one wall of the microchannel (2). At least two different types of bubbles or drops (14, 15) carried by the first fluid;
The channel (3) constitutes means for sorting or classifying the bubbles or drops so that only the first type of bubbles or drops (15) are guided into the channel (3). A circuit according to claim 1 or 2, characterized in that The circuit according to claim 3, characterized in that said at least two different types of bubbles or drops (5) have different sizes, viscosities or surface tensions.   Said flow path (3) has at least two successive parts (17, 18, 19, 20) of different heights and / or widths, of these parts having a larger height and / or width. 5. A circuit according to any one of the preceding claims, characterized in that the part is arranged in front of the part of small height and / or width in the direction of the first fluid flow. .   6. The circuit according to claim 1, comprising a plurality of channels (3) having different widths and / or different slopes relative to the flow of the first fluid.   By enlarging the cross-section of the passage of drops or bubbles (5) in the microchannel (2) or the flow path (3) or of the surface energy of the microchannel (2) and / or the flow path (3) A circuit according to any one of the preceding claims, characterized in that it comprises a plurality of trapping areas (28) for catching drops or bubbles (5) that are formed by partial modification. . The circuit of claim 7, wherein at least some of the plurality of trap regions (28) are independent of each other. The at least some of the plurality of trap regions (28) are connected in series or in parallel by the microchannel (2) or by the flow path (3). Circuit described in. The obstacle (32) is formed downstream of a predetermined trap region of the plurality of trap regions so as to hold bubbles or droplets drawn into the trap region in the trap region. 10. A circuit according to any one of claims 7 to 9, characterized in that:   Said at least one channel (3) comprises means (25) for decelerating or accelerating bubbles or drops (5) present in said channel (3). The means (25) for decelerating or the means (26) for accelerating is a predetermined region for decelerating or accelerating by deformation of the width or height of the flow path (3). 11. A circuit according to any one of the preceding claims, characterized in that it is formed by a corresponding rail or rib of the wall of the microchannel formed along the line. Means (38) for supplying parallel flow of different types of drops or bubbles (21, 22, 23, 24) into the microchannel (2), and drops or bubbles of different characteristics to the microchannel (2) comprising parallel means (39) for introduction into,
It said flow path (3), the droplets or bubbles exiting from each of the parallel means (39) for the introduction, to guide to a predetermined area in front Symbol microchannel (2), in the microchannel Formed ,
Circuit according to any one of claims 1 to 11, characterized in that.

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